U.S. Pat. No. 6,273,613 describes a pin bearing arrangement for use on an aircraft landing gear wherein the pin includes strain gauges for measuring shear loads sustained by the pin. The bearing pin is used to measure loads during testing of aircraft landing gear, in particular during development and design of a landing gear. When measuring loads with a pin such as that disclosed in U.S. Pat. No. 6,273,613 it is necessary to connect the outputs of the strain gauges to one of the aircraft's computer systems. This connection is typically provided by means of wires carrying electronic signals from the strain gauges to the aircraft computer system or specially provided separate data logging equipment. For example, in one known system, the signals from the strain gauges are recorded by means of a data recorder that is provided in the pressurised cabin of the aircraft. The data is received by the recorder by means of wires leading from the strain gauges via signal conditioning units mounted in the landing gear bay. The power required to operate that system is drawn from the aircraft system power supply. Thus the installation of such load measuring pins is cumbersome and time consuming. Furthermore, as a result of there being a physical connection from a portion of the landing gear to the aircraft computer the reliability of the load measuring system depends on a good connection being maintained by the wiring all the way between the pin and the computer system. Also, such an arrangement needs to be regularly maintained, requiring further labour. As a result of such disadvantages such load measurement systems are typically only used during testing and certification procedures and are therefore of limited use.
The present invention seeks to provide an improved apparatus and method for measuring loads sustained by bearing pins. Alternatively or additionally, the present invention seeks to provide an apparatus or method for measuring the load sustained by a bearing pin that mitigates one or more of the above-mentioned disadvantages with the acknowledged prior art.